A Finite Element Model of the Human Knee Joint for the Study of Tibio-Femoral Contact

Abstract

As a step towards developing a finite element model of the knee that can be used to study how the variables associated with a meniscal replacement affect tibio-femoral contact, the goals of this study were 1) to develop a geometrically accurate three-dimensional solid model of the knee joint with special attention given to the menisci and articular cartilage, 2) to determine to what extent bony deformations affect contact behavior, and 3) to determine whether constraining rotations other than flexion/extension affects the contact behavior of the joint during compressive loading. The model included both the cortical and trabecular bone of the femur and tibia, articular cartilage of the femoral condyles and tibial plateau, both the medial and lateral menisci with their horn attachments, the transverse ligament, the anterior cruciate ligament, and the medial collateral ligament. The solid models for the menisci and articular cartilage were created from surface scans provided by a noncontacting, laser-based, three-dimensional coordinate digitizing system with an root mean squared error (RMSE) of less than 8 microns. Solid models of both the tibia and femur were created from CT images, except for the most proximal surface of the tibia and most distal surface of the femur which were created with the three-dimensional coordinate digitizing system. The constitutive relation of the menisci treated the tissue as transversely isotropic and linearly elastic. Under the application of an 800 N compressive load at 0 degrees of flexion, six contact variables in each compartment (ie., medial and lateral) were computed including maximum pressure, mean pressure, contact area, total contact force, and coordinates of the center of pressure. Convergence of the finite element solution was studied using three mesh sizes ranging from an average element size of 5 mm by 5 mm to 1 mm by 1 mm. The solution was considered converged for an average element size of 2 mm by 2 mm. Using this mesh size, finite element solutions for rigid versus deformable bones indicated that none of the contact variables changed by more than 2% when the femur and tibia were treated as rigid. However, differences in contact variables as large as 19% occurred when rotations other than flexion/extension were constrained. The largest difference was in the maximum pressure. Among the principal conclusions of the study are that accurate finite element solutions of tibio-femoral contact behavior can be obtained by treating the bones as rigid. However, unrealistic constraints on rotations other than flexion/extension can result in relatively large errors in contact variables.

Influence of Meniscectomy and Meniscus Replacement on the Stress Distribution in Human Knee Joint

“…[26][27][28]59 Analysis of the stress distribution in human knee joint can help immensely in understanding the underlying mechanisms and causes of cartilage degeneration and have direct implication in prevention of pathological degeneration of the cartilage and injury and in tissue engineering. 17,32,44,47,49,59,60 Load-induced articular cartilage damage is generally classified into; Type 1: Damage without disruption of the underlying bone or calcified cartilage layer, and Type 2: Subchondral fracture with or without damage to the overlying articular cartilage. 5 Several theoretical models predicted that the maximum level of shear stress in the articular cartilage of the knee joint occurs at the bonecartilage interface.…”

Evaluation of an intact, an ACL-deficient, and a reconstructed human knee joint finite element model

“…This is due to the material properties used for the meniscus in this model. In literature, the material properties of the meniscus show a wide range in values, with Young's modulus varying from 3 MPa (Donahue et al 2002) used in this study up to 59 MPa (Peña et al 2006). This wide variation is due to the different samples used in each study.…”

The Effect of Ligament Modeling Technique on Knee Joint Kinematics: A Finite Element Study

“…Following assembly, proper material properties taken from literature were assigned to each segment [1,2,5,13–20]. Bones were modeled as linear elastic [21–25] with different moduli assigned to cortical and trabecular regions consistent with earlier FE studies of the human knee joint [2,13]. Tibiofemoral and patellofemoral articular cartilage were modeled as isotropic linear elastic [16].…”